package com.bumptech.glide.load;

import com.bumptech.glide.load.engine.Resource;
import ohos.app.Context;
import org.jetbrains.annotations.NotNull;

import java.nio.charset.Charset;
import java.security.MessageDigest;

/**
 * A class for performing an arbitrary transformation on a resource that implements {@link
 * #equals(Object)} and {@link #hashCode()}} to identify the transformation in the memory cache and
 * {@link #updateDiskCacheKey(MessageDigest)}} to identify the transformation in disk
 * caches.
 *
 * <p>Using the fully qualified class name as a static final {@link String} (not {@link
 * Class#getName()} to avoid proguard obfuscation) is an easy way to implement {@link
 * #updateDiskCacheKey(MessageDigest)}} correctly. If additional arguments are
 * required they can be passed in to the constructor of the {@code Transformation} and then used to
 * update the {@link MessageDigest} passed in to {@link
 * #updateDiskCacheKey(MessageDigest)}. If arguments are primitive types, they can typically easily
 * be serialized using {@link java.nio.ByteBuffer}. {@link String} types can be serialized with
 * {@link String#getBytes(Charset)} using the constant {@link #CHARSET}.
 *
 * <p>Implementations <em>must</em> implement {@link #equals(Object)} and {@link #hashCode()} for
 * memory caching to work correctly.
 *
 * @param <T> The type of the resource being transformed.
 */
public interface Transformation<T> extends Key {

  /**
   * Transforms the given resource and returns the transformed resource.
   *
   * <p>If the original resource object is not returned, the original resource will be recycled and
   * it's internal resources may be reused. This means it is not safe to rely on the original
   * resource or any internal state of the original resource in any new resource that is created.
   * Usually this shouldn't occur, but if absolutely necessary either the original resource object
   * can be returned with modified internal state, or the data in the original resource can be
   * copied into the transformed resource.
   *
   * <p>If a Transformation is updated, {@link #equals(Object)}, {@link #hashCode()}, and {@link
   * #updateDiskCacheKey(MessageDigest)} should all change. If you're using a simple
   * String key an easy way to do this is to append a version number to your key. Failing to do so
   * will mean users may see images loaded from cache that had the old version of the Transformation
   * applied. Changing the return values of those methods will ensure that the cache key has changed
   * and therefore that any cached resources will be re-generated using the updated Transformation.
   *
   * <p>During development you may need to either using {@link
   * com.bumptech.glide.load.engine.DiskCacheStrategy#NONE} or make sure {@link
   * #updateDiskCacheKey(MessageDigest)} changes each time you make a change to the
   * Transformation. Otherwise the resource you request may be loaded from disk cache and your
   * Transformation may not be called.
   *
   * @param context The Application context
   * @param resource The resource to transform.
   * @param outWidth The width of the view or target the resource will be displayed in, or {@link
   *     com.bumptech.glide.request.target.Target#SIZE_ORIGINAL} to indicate the original resource
   *     width.
   * @param outHeight The height of the view or target the resource will be displayed in, or {@link
   *     com.bumptech.glide.request.target.Target#SIZE_ORIGINAL} to indicate the original resource
   *     height.
   * @return The transformed resource.
   */
  @NotNull
  Resource<T> transform(
      @NotNull Context context, @NotNull Resource<T> resource, int outWidth, int outHeight);
}
